Conventionally, in image forming apparatuses such as scanners, copiers, and multifunction peripherals (MFP), with an illuminating apparatus and a lens array having plural lenses arranged in the array, an image formed on an original document is focused onto an image sensor where the image is read or “imaged” to be read. In addition, in printers, copiers, multifunction peripherals (MFP), or other image forming apparatuses, an LED or other light emitting device and a lens array are used to cause the light rays from the LED pass through the lens array to form an image on a photoreceptor drum (exposure). Here, the lens array is formed as a combination of lenses and apertures.
However, for the lens array, if the optical axis of the different lenses that are used for the passing of a light rays are offset from each other, the resulting unevenness in the imaging characteristics and the light quantity degrades the image significantly. Also, when plural lenses, mirrors and apertures are combined to form the imaging optics, misalignment during the assembly of the imaging optics leads to degradation in the performance of, and a rise in the manufacturing cost of, the image forming apparatus.